nameserv::protocol(n)					       Name service facility					     nameserv::protocol(n)

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NAME

       nameserv::protocol - Name service facility, client/server protocol

SYNOPSIS

       Bind name data

       Release

       Search pattern

       ProtocolVersion

       ProtocolFeatures

       Search/Continuous/Start tag pattern

       Search/Continuous/Stop tag

       Search/Continuous/Change tag add|remove response

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DESCRIPTION

       The  packages  nameserv::server, nameserv, and nameserv::common provide a simple unprotected name service facility for use in small trusted
       environments.

       Please read Name service facility, introduction first.

       This document contains the specification of the network protocol which is used by client and server to talk to each other, enabling  imple-
       mentations of the same protocol in other languages.

NANO NAME SERVICE PROTOCOL VERSION 1
       This protocol defines the basic set of messages to be supported by a name service, also called the Core feature.

   BASIC LAYER
       The basic communication between client and server is done using the remote-execution protocol specified by the Tcl package comm.  The rele-
       vant document specifying its on-the-wire protocol can be found in comm_wire.

       All the scripts exchanged via this protocol are single commands in list form and thus can be interpreted as plain messages  instead  of	as
       Tcl commands. The commands/messages specified in the next section are the only commands understood by the server-side. Command and variable
       substitutions are not allowed within the messages, i.e. arguments have to be literal values.

       The protocol is synchronous. I.e. for each message sent a response is expected, and has to be generated.  All  messages	are  sent  by  the
       client.	The server does not sent messages, only responses to messages.

   MESSAGE LAYER
       Bind name data
	      The  client  sends this message when it registers itself at the service with a name and some associated data. The server has to send
	      an error response if the name is already in use. Otherwise the response has to be an empty string.

	      The server has to accept multiple names for the same client.

       Release
	      The client sends this message to unregister all names it is known under at the service. The response has	to  be	an  empty  string,
	      always.

       Search pattern
	      The  client  sends  this message to search the service for names matching the glob-pattern. The response has to be a dictionary con-
	      taining the matching names as keys, and mapping them to the data associated with it at Bind-time.

       ProtocolVersion
	      The client sends this message to query the service for the highest version of the name service protocol it  supports.  The  response
	      has to be a positive integer number.

	      Servers supporting only Nano Name Service Protocol Version 1 have to return 1.

       ProtocolFeatures
	      The client sends this message to query the service for the features of the name service protocol it supports. The response has to be
	      a list containing feature names.

	      Servers supporting only Nano Name Service Protocol Version 1 have to return {Core}.

NANO NAME SERVICE PROTOCOL EXTENSION
: CONTINUOUS SEARCH
       This protocol defines an extended set of messages to be supported by a name service, also called the Search/Continuous feature.	This  fea-
       ture  defines  additional messages between client and server, and is otherwise identical to version 1 of the protocol. See the last section
       for the details of our foundation.

       A service supporting this feature has to put the feature name Search/Continuous into the list of features returned by  the  message  Proto-
       colFeatures.

       For  this  extension the protocol is asynchronous. No direct response is expected for any of the messages in the extension. Furthermore the
       server will start sending messages on its own, instead of only responses to messages, and the client has to be able to handle these notifi-
       cations.

       Search/Continuous/Start tag pattern
	      The client sends this message to start searching the service for names matching the glob-pattern.  In contrast to the regular Search
	      request this one asks the server to continuously monitor the database for the addition and removal of matching entries and to notify
	      the client of all such changes. The particular search is identified by the tag.

	      No  direct  response is expected, rather the clients expect to be notified of changes via explicit Search/Continuous/Result messages
	      generated by the service.

	      It is further expected that the tag information is passed unchanged to the Search/Continuous/Result messages. This  tagging  of  the
	      results enables clients to start multiple searches and distinguish between the different results.

       Search/Continuous/Stop tag
	      The client sends this message to stop the continuous search identified by the tag.

       Search/Continuous/Change tag add|remove response
	      This message is sent by the service to clients with active continuous searches to transfer found changes. The first such message for
	      a new continuous search has to contains the current set of matching entries.

	      To ensure this a service has to generate an add-message with an empty response if there were no matching entries at the time.

	      The response has to be a dictionary containing the matching names as keys, and mapping them to the data associated with it at  Bind-
	      time.   The  argument  coming  before the response tells the client whether the names in the response were added or removed from the
	      service.

BUGS, IDEAS, FEEDBACK
       This document, and the package it describes, will undoubtedly contain bugs and other problems.  Please report such in the category nameserv
       of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883].  Please also report any ideas for enhancements you may have for
       either package and/or documentation.

SEE ALSO

       comm_wire(n), nameserv(n), nameserv::server(n)

KEYWORDS

       comm, name service, protocol

COPYRIGHT

       Copyright (c) 2007-2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>

nns									0.1						     nameserv::protocol(n)